Electronic Supplementary Material (ESI) for Green Chemistry. This journal is The Royal Society of Chemistry 2017 Supplementary Information Effect of room temperature ionic liquids on selective biocatalytic hydrolysis of chitin via sequential or simultaneous strategies E. Husson, a C. Hadad, b,c G. Huet, a,b,c S. Laclef, b,c D. Lesur, b,c V. Lambertyn, a A. Jamali, c,d S. Gottis, e,c C. Sarazin, a A. Nguyen Van Nhien, b,c a. Unité de Génie Enzymatique et Cellulaire, FRE CNRS 3580, Université de Picardie Jules Verne - UFR des Sciences, 33 rue Saint Leu - 80039 Amiens Cedex 1, France. b. Laboratoire de Glycochimie, des Antimicrobiens et des Agroressources, UMR CNRS 7378, Université de Picardie Jules Verne, 33 rue Saint Leu - UFR des Sciences 80039 cedex Amiens, France. c. Institut de Chimie de Picardie, FR CNRS 3085, Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex, France d. Plateforme de Microscopie Electronique - Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex, France. e. Laboratoire de Réactivité et de Chimie des Solides, UMR CNRS 7314 - Université de Picardie Jules Verne, 33 rue Saint Leu - 80039 Amiens Cedex, France. Corresponding author: albert.nguyen-van-nhien@u-picardie.fr ------------------------------------------------------------------ Table of contents 1. Selected room temperature ionic liquids p.2 2. Characteristic HPLC chromatograms p.3 3. SEM micrographs p.4 4. Solid-state 13 C NMR p.6 5. Infra-Red spectra p.8 6. Mass spectra of isolated hydrolysis products p.9 7. Solubility test of chitin in room temperature ionic liquids p.10 8. Best experimental procedure to efficiently produce N-acetylglucosamine p.11 9. Best experimental procedure to efficiently produce N,N -diacetylchitobiose p.11 1
1. Selected room temperature ionic liquids Table S1. Chemical structure and corresponding physico-chemical properties of the two distinct room temperature imidazolium-based ionic liquids used in this study a. a Data from Solvionic SA (Verniolle, France) index; b From C. Froschauer, M. Hummel, M. Iakovlev, A. Roselli, H. Schottenberger, and H. Sixta, Biomacromolecules 2013, 14: 1741-1750; c From Y. Fukaya, K. Hayashi, M. Wada and H. Ohno, Green Chem., 2008, 10: 44-46. ND: not determined. 2
2. Characteristic HPLC chromatograms t r = 11.995 min (a) t r = 14.608 min (b) Figure S1. Characteristic HPLC chromatograms of: (a) standard N,N -diacetylchitobiose (blue line) and supernatant of hydrolysate (black line) obtained by enzymatic hydrolysis of [C 2 mim][oac]-pretreated chitin in aqueous buffer catalyzed by the chitinase from S. griseus for 24h and (b) standard N- acetylglucosamine (pink line) and supernatant of hydrolysate (black line) obtained by enzymatic hydrolysis of [C 2 mim][oac]-pretreated chitin in aqueous buffer. This reaction was catalyzed by the chitinase from S. griseus for 24h then supplemented by the chitinase from T. viride for 12h. identified as enzymes preparation and aqueous buffer. 3
3. SEM micrographs 400 µm 50 µm 40 µm Figure S2. SEM images of untreated chitin. 4
500 µm Figure S3. SEM images of [C 2 mim][meo(h)po 2 ]-pretreated chitin. 50 µm 10 µm Figure S4. SEM images of [C 2 mim][oac]-pretreated chitin. 5
4. Solid-state 13 C NMR Solid-state 13 C NMR spectra were obtained with 4 mm CP-MAS probe operating at 125.7452 MHz on a Bruker DRX 500 at 25 C. The spinning rate was 5 khz with 2 ms contact times and 5 s delay between scans (2048 scans). The degree of acetylation (DA) corresponds to the ratio of integrated methyl peak area to the sum of integrated carbons peaks. The chemical shifts were externally referred by setting the carbonyl resonance of glycine to 176.03 ppm. Ref: Kasaai, M. J. Agric. Food Chem. 2009, 57, 1667-1676. Younes, I.; Rinaudo, M. Mar. Drugs 2015, 13, 1133-1174. Heux, L.; Brugnerotto, J.; Desbrière, J.; Versali, M.-F.; Rinaudo, M. Biomacromolecules 2000, 1, 746-751. Duarte, M. L.; Ferreira, M. C.; Marvao, M. R.; Rocha, J. Int. J. Biol. Macromolec. 2001, 28, 359-363. CP-MAS 13 C NMR (25 C, 125 MHz): δ C 173.8 (C=O), 104.1 (C1), 83.0 (C4), 75.7 (C5), 73.3 (C3), 60.8 (C6), 55.2 (C2), 22.8 (CH 3 ). 0.43 1.20 5.68 1.00 173.2 104.1 83.0 75.7 73.3 60.8 55.0 22.8 C3 C5 CH 3 C1 C2 Spinning side band for C=O C4 C6 C=O 240 230 220 210 200 190 180 170 160 150 140 130 120 110 f1 (ppm) 100 90 80 70 60 50 40 30 20 10 0-10 -2 Figure S5. Solid-state CP-MAS 13 C NMR spectrum of untreated chitin (DA = 87%). 6
0.54 1.13 5.43 1.00 174.0 103.9 83.3 75.5 73.5 61.1 55.1 22.8 C5 C3 CH 3 C2 C1 C6 Spinning side band for C=O C4 C=O 50 240 230 220 210 200 190 180 170 160 150 140 130 120 110 f1 (ppm) 100 90 80 70 60 50 40 30 20 10 0-10 Figure S6. Solid-state CP-MAS 13 C NMR spectrum of [C 2 mim][oac]-pretreated chitin (DA = 91%). 0.53 1.09 5.25 1.00 173.9 104.2 83.0 75.7 73.3 60.8 55.0 22.8 C3 C5 CH 3 C1 C2 Spinning side band for C=O C4 C6 C=O 50 240 230 220 210 200 190 180 170 160 150 140 130 120 110 f1 (ppm) 100 90 80 70 60 50 40 30 20 10 0-10 -2 Figure S7. Solid-state CP-MAS 13 C NMR spectrum of [C 2 mim][meo(h)po 2 ]-pretreated chitin (DA = 94%). 7
5. Infra-Red spectra 100 98 T (%) 96 94 92 Chitin C 2 mim][oac]-pretreated chitin [C 2 mim][meo(h)po 2 ]-pretreated chitin 4000 3500 3000 2500 2000 1500 1000 Wavenumber (cm -1 ) Figure S8. IR spectra of untreated chitin (black line), [C 2 mim][oac]-pretreated chitin (red line) and [C 2 mim][meo(h)po 2 ]-pretreated chitin (blue line). 8
6. Mass spectra of isolated hydrolysis products Figure S9. ESI-MS spectrum of the isolated N-acetylglucosamine. Figure S10. ESI-MS spectrum of the isolated N,N -diacetylchitobiose 9
7. Solubility test of chitin in room temperature ionic liquids The experimental procedure used for this solubility test was adapted from the one proposed by Fukaya et al about dissolution studies of recalcitrant polysaccharide in RTIL. Suspensions of commercial chitin (0.05, 0.1, 0.2, 0.5, 1.0 and 1.5 and 2.0 % w/v) were incubated in [C 2 mim][oac] and [C 2 mim][meo(h)po 2 ] at 110 C for 40 min under vigorous stirring. The highest concentration leading to a clear solution was evaluated as the maximal solubility value. In [C 2 mim][oac], clear solutions were observed for 0.05 % and 0.1 % w/v of chitin whereas no clear solution was recorded for [C 2 mim][meo(h)po 2 ] as depicted above. Ref: Y. Fukaya, K. Hayashi, M. Wada and H. Ohno, Green Chem., 2008, 10, 44-46. Figure S11. Solubilization test of chitin in [C 2 mim][oac] (a) and [C 2 mim][meo(h)po 2 ] (b) at 110 C for 40 min. 10
8. Best experimental procedure to efficiently produce N-acetylglucosamine Chitin (2% w/v) was added to 10 ml of [C 2 mim][oac], and incubated in an oil bath at 110 C with stirring for 40 min. After incubation, each chitin suspension was cooled in an ice bath. The pretreated chitin was precipitated by adding 20 ml of ultra-pure water (deionized water with a resistivity of 18.3 MΩ cm, Barnsted Easy Pure RF) to the mixture (v/v) with vigorous stirring for 30 min in order to increase the polarity of the medium. After a centrifugation step (10,733 g, 20 min, 4 C with an Allegra 64R Beckman Coulter Rotor: F0850), the supernatant containing [C 2 mim][oac] and water was kept for future recycling. The pretreated chitin powder was collected by vacuum filtration thoroughly and washed with ultra-pure water. The resulting solid was then poured into ultra-pure water, sonicated for 5 minutes and collected again by vacuum filtration. This step was repeated 5 times before freeze drying the product. 10 mg of [C 2 mim][oac]-pretreated chitin were added to 0.9 ml of phosphate buffer (10 mm, ph 6.0) and incubated for 30 min (40 C; 1000 rpm). After this pre-incubation step, hydrolysis was initiated by addition of 100 L of 1 mg/ml chitinase from S. griseus preparation. After 24 h of reaction, the second chitinase from T. viride was added to the first one. After 12 h, enzymatic reaction was stopped by incubating at 90 C for 20 min to deactivate both enzymes. Supernatant was diluted in ultra-pure water and filtered (0.2 μm) prior to analysis by HPLC. The conversion yield into N-acetylglucosamine was 760.0 ± 0.1 mg / g chitin. 9. Best experimental procedure to efficiently produce N,N -diacetylchitobiose Chitin (2% w/v) was added to 10 ml of [C 2 mim][oac], and incubated in an oil bath at 110 C with stirring for 40 min. After incubation, each chitin suspension was cooled in an ice bath. The pretreated chitin was precipitated by adding 20 ml of ultra-pure water (deionized water with a resistivity of 18.3 MΩ cm, Barnsted Easy Pure RF) to the mixture (v/v) with vigorous stirring for 30 min in order to increase the polarity of the medium. After a centrifugation step (10,733 g, 20 min, 4 C with an Allegra 64R Beckman Coulter Rotor: F0850), the supernatant containing [C 2 mim][oac] and water was kept for future recycling. The pretreated chitin powder was collected by vacuum filtration thoroughly and washed with ultra-pure water. The resulting solid was then poured into ultra-pure water, sonicated for 5 minutes and collected again by vacuum filtration. This step was repeated 5 times before freeze drying the product. 10 mg of [C 2 mim][oac]-pretreated chitin were added to 0.9 ml of phosphate buffer (10 mm, ph 6.0) and incubated for 30 min (40 C; 1000 rpm). After this pre-incubation step, hydrolysis was initiated by addition of 100 L of 1 mg/ml chitinase from S. griseus preparation. After 48 h of reaction, enzymatic reaction was stopped by incubating at 90 C for 20 min to deactivate the enzyme. Supernatant was diluted in ultra-pure water and filtered (0.2 μm) prior to analysis by HPLC. The conversion yield into N,N -diacetylchitobiose was 705.0 ± 5.0 mg / g. 11